Field of the Invention
This invention relates to an optical device. It arose in relation to the design of gun sights but could possibly be applicable to other areas of optics. In this specification the terms "optical" and "optics" are to be construed as including visible, infra-red, ultra-violet and any other lens and/or mirror systems.
In operation of a gun sight the gunner sometimes needs to view subjects outside the field of view of the sight and, in order to do so, needs to move the sight so as to change its field of view. This either involves moving the gun, which may be undesirable because such movement can be detected by others; or involves moving the sight relative to the gun. Moving the sight relative to the gun introduces the problem of subsequently needing to re-align the sight with the gun.